Processes for batchwise sterilization of a product in an autoclave are known at present.
Such a sterilization is performed under pressure, for example 3 bar, and consists in heating the receptacles containing the product to be sterilized to of the order of 120.degree. C. for 10 to 30 minutes.
Such processes have disadvantages. They do not permit easy continuous operation. Once the products are sterilized and then conveyed towards their destinations, no subsequent control can be performed in the event of doubt concerning the sterilization of said products.
The present invention is aimed at providing a process, a device, a marking support and a receptacle for product to be controlled corresponding better than those previously known to the requirements of the practice, especially insofar as it permits a true dosimetric control proving that the product has been heated to a temperature exceeding a determined threshold temperature, for example of the order of 120.degree. C., for a period longer than a determined threshold period, for example twenty minutes, and does this with extreme ease; the control can be performed at any time by an operator who is not specially qualified, with the aid of a simple ohmmeter.
To do this, the invention starts with the idea of employing microwave energy, on the one hand for rapidly and homogeneously heating the product and, on the other hand, for varying the conductivity of a thermally crosslinkable ink with which the product or the receptacle containing the product to be heated has been previously marked.
The inventors have, in fact, had the idea of employing the process of crosslinking under microwaves of inks of the polymeric type which are filled with conductive particles like metal powders or fibers such as silver, copper, iron, manganese, ruthenium, rhenium, rhodium, nickel, aluminum or like carbon black, by converting an insulating product into conductive product, to make it act as a dosimeter, in order to control the sterilization of a product, and especially of an injectable solution.